Budapest, including the Banks of the Danube, the Buda Castle Quarter and Andrássy Avenue has the remains of monuments such as the Roman city of Aquincum and the Gothic castle of Buda, which have had a considerable influence on the architecture of various periods. It is one of the world's outstanding urban landscapes and illustrates the great periods in the history of the Hungarian capital.

The Historic Centre of Budapest  was inscribed on the World Heritage List in 1987.

Budapest is the capital city of Hungary and the country's principal political, cultural, commercial, industrial and transportation center.

Budapest has over 1.7 million inhabitants, down from a mid-1980s peak of 2.1 million. Budapest became a single city occupying both banks of the river Danube with the amalgamation in 17 November 1873 of right-bank Buda (Ofen in German) and Óbuda (Old Buda or Alt-Ofen) together with Pest on the left (east) bank. It is the seventh largest city in the European Union.

During the 20th century, most population growth occurred in the suburbs, with Újpest more than doubling between 1890–1910 and Kispest more than quintupling in 1900–1920, as much of the country's industry came to be concentrated in the city. The country's human losses during World War I and the subsequent loss of more than two thirds of the former kingdom's territory (1920) dealt only a temporary blow, leaving Budapest as the capital of a smaller but now sovereign state. By 1930 the city proper contained a million inhabitants, with a further 400,000 in the suburbs.

Between 20% and 40% of Greater Budapest's 250,000 Jewish inhabitants died through Nazi and Arrow Cross genocide during 1944 and early 1945.  Despite this, Budapest today has the highest number of Jewish citizens per capita of any European city.

On January 1, 1950, the area of Budapest was significantly expanded: new districts were formed from the neighbouring cities and towns (see Great-Budapest). From the severe damage during the Soviet siege in 1944, the city recovered in the 1950s and 1960s, becoming to some extent a showcase for the more pragmatic policies pursued by the country's communist government (1947–1989) from the 1960s. Since the 1980s, the capital has shared with the country as a whole in increased emigration (mostly to the agglomeration) coupled with natural population decrease.